Bricked a 5.5GEN -B

I was trying to update my software from 5.5 GEN -B to the latest custom firmware.
I have a 1.5 fat PSP.Downloaded a copy of hellcats downgrader, as I found no other way to undo the GEN-B.Followed every singles step correctly, the downgrade went fine, until the last step->the restart , after Hellcats downgrading.Now I do not find any display when I switch on my PSP(I have tried removing the MS, battery), and still no display however pressing all combinations of buttons.It simply wont give any display.